Your 1st specimen is Cheilomenes sexmaculata (Coccinelidae) and 2nd specimen looks like Nephus lentiformis (Coccinelidae). Your 3 third specimen is Diapromorpha near turcica (Chrysomelidae). The first two are predators of other insects (beneficial ) and the third one is a pest. It causes defoliation by making small holes on leaf lamina.